The present invention relates generally to semiconductor device packages, and more particularly to radio frequency shielded semiconductor device packages.
Semiconductor device packages or integrated circuit chip carriers are used in many high-density electronics applications. The integrated circuits or semiconductor devices are protected from the external environment by encapsulation with an epoxy material or transfer molding a thermoplastic resin about the device. However, the plastic encapsulant does not provide shielding from radiation, such as radio frequency interference (RFI) or electromagnetic interference (EMI).
As circuits become smaller, denser, and operate at higher frequencies and in harsher environments, there is a growing need to shield the circuits from radiation, such as radio frequency interference (RFI) and electromagnetic interference (EMI). For example, cell phones and other mobile devices need to be protected from such radiation. Automotive circuits, such as microcontrollers that are mounted near the spark plugs also need to be shielded. Conventional packages do not protect the semiconductor devices within them from such electromagnetic waves.
Conventional shielding systems use a conductive metallic enclosure that surrounds the circuit to be shielded. The enclosure protects the internal circuit from EMI and RFI and prevents the escape of RFI or EMI signals generated by the circuit. Another solution is to place a metal cap over a semiconductor device prior to molding the package. This solution is applicable to ball grid array (BGA) packages that have a large semiconductor die (i.e., at least one inch squared). Yet another solution is to provide a metal coating over the encapsulated device. However, all of these solutions have some drawbacks. For instance, using a conductive metal enclosure adds to the overall size of the package and requires an additional soldering step to attach the metal shield to the device, with the heat generated by the additional soldering process potentially harming the device.
Therefore, a need exists for cost-effective, component level shielding that can be used in a variety of packages with any semiconductor die size.
Those of skill in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve the understanding of the embodiments of the present invention.